Wireless power transmitter

ABSTRACT

Disclosed is a wireless power transmitter. The wireless power transmitter includes a coil in a first case; a first passage groove having a shape corresponding to a shape of the first case; and a second case coupled to the first case.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority under 35 U.S.C. §119(a) ofKorean Patent Application No. 10-2012-0146957 filed on Dec. 14, 2012,which is hereby incorporated by reference in its entirety.

BACKGROUND

The embodiment relates to a wireless power transmission technology. Moreparticularly, the embodiment relates to a wireless power transmitter ofwirelessly transmitting electric power.

A wireless power transmission or a wireless energy transfer refers to atechnology of wirelessly transferring electric energy to desireddevices. In the 1800's, an electric motor or a transformer employing theprinciple of electromagnetic induction has been extensively used andthen a method for transmitting electrical energy by irradiatingelectromagnetic waves, such as radio waves or lasers, has beensuggested. Actually, electrical toothbrushes or electrical razors, whichare frequently used in daily life, are charged based on the principle ofelectromagnetic induction. The electromagnetic induction refers to aphenomenon in which voltage is induced so that current flows when amagnetic field is varied around a conductor. Although thecommercialization of the electromagnetic induction technology has beenrapidly progressed around small-size devices, the power transmissiondistance thereof is short.

Until now, wireless energy transmission schemes include a remotetelecommunication technology based on a magnetic resonance scheme and ashort wave radio frequency scheme in addition to the electromagneticinduction scheme.

Recently, among wireless power transmitting technologies, an energytransmitting scheme employing the electromagnetic induction scheme andthe resonance scheme has been widely used.

Since a wireless power transmission system based on the electromagneticinduction scheme and the resonance scheme transmits electrical signalsformed at transmitter and receiver sides through a coil in wireless, auser can easily charge an electronic device such as a portable devicewith electricity.

However, according to the related art, heat is generated from thetransmission coil included in the wireless power transmitter due to aresistance component when current flows through the transmission coil,so that the wireless power transmitter is deteriorated. Thus, the heatis transferred to the wireless power receiver placed on the wirelesspower transmitter, so that the wireless power receiver is deteriorated.

One example of the related art is disclosed in Korean Patent UnexaminedPublication No. 10-2007-0080057 entitled “Contactless charger systemhaving heat-dissipating means and charging unit thereof”.

BRIEF SUMMARY

The embodiment provides a wireless power transmitter capable ofeffectively radiating the heat of electronic components including atransmission coil.

According to an embodiment, there is provided a wireless powertransmitter including a first case; a coil on the first case; a firstpassage groove having a shape corresponding to a shape of the coil; anda second case coupled to the first case.

According to another embodiment, there is provided a wireless powertransmitter including a transmission coil to wirelessly transmit powerto a wireless power receiver; an inlet device on one side of thetransmission coil to supply air to the transmission coil; and aradiation unit to radiate heat of the transmission coil by changing amovement path of the supplied air.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a wireless power transmission systemaccording to a first embodiment.

FIG. 2 is a block diagram showing a wireless power transmission systemaccording to a second embodiment.

FIG. 3 is a block diagram showing a wireless power transmission systemaccording to a third embodiment.

FIG. 4 is an equivalent circuit diagram of the transmission inductioncoil according to an embodiment.

FIG. 5 is an equivalent circuit diagram of the power supply device andthe wireless power transmitter according to an embodiment.

FIG. 6 is an equivalent circuit diagram of the wireless power receiveraccording to an embodiment.

FIG. 7 is a block diagram showing a power supply device according to anembodiment.

FIG. 8 is an exploded perspective view showing a wireless powertransmitter according to an embodiment.

FIG. 9 is a plan projection view showing a wireless power transmitteraccording to an embodiment.

FIG. 10 is a plane projection view of the wireless power transmitter forthe purpose of illustrating a process of radiating heat generated fromthe wireless power transmitter according to an embodiment.

FIG. 11 is a view illustrating a variation of temperature near thetransmission coil according to whether the wireless power transmitter ofthe embodiment is used.

FIG. 12 is a view showing properties of the elements of the wirelesspower transmitter 200 according to an embodiment.

FIG. 13 is a view illustrating a variation of temperature near the powersupply device according to whether the wireless power transmitter of theembodiment is used.

DETAILED DESCRIPTION

Hereinafter, embodiments will be described with reference toaccompanying drawings. The thickness and size of each layer shown in thedrawings may be exaggerated, omitted or schematically drawn for thepurpose of convenience or clarity. In addition, the size of elementsdoes not utterly reflect an actual size.

FIG. 1 is a block diagram showing a wireless power transmission systemaccording to a first embodiment.

Referring to FIG. 1, the wireless power transmission system 10 mayinclude a power supply device 100, a wireless power transmitter 200, awireless power receiver 300 and a load 400.

The wireless power transmission system 10 shown in FIG. 1 may be asystem in which the wireless power transmitter 200 wirelessly transmitspower to the wireless power receiver 300 in a resonance scheme.

According to an embodiment, the power supply device 100 may be includedin the wireless power transmitter 200, but the embodiment is not limitedthereto.

The wireless power transmitter 200 may include a transmission inductioncoil 210 and a transmission resonant coil 220.

The wireless power receiver 300 may include a reception resonant coil310, a reception induction coil 320 and a rectifying circuit 330.

Both terminals of the power supply device 100 are connected to bothterminals of the transmission induction coil 210.

The transmission resonant coil 220 may be spaced apart from thetransmission induction coil 210 by a predetermined distance.

The reception resonant coil 310 may be spaced apart from the receptioninduction coil 320 by a predetermined distance.

Both terminals of the reception induction coil 320 are connected to bothterminals of the rectifying circuit 330, and the load 400 is connectedto both terminals of the rectifying circuit 330. According to anembodiment, the load 400 may be included in the wireless power receiver300.

The power generated from the power supply device 100 is transmitted tothe wireless power transmitter 200. The power received in the wirelesspower transmitter 200 is transmitted to the wireless power receiver 300that makes resonance with the wireless power transmitter 200 due to aresonance phenomenon, that is, has the resonance frequency the same asthat of the wireless power transmitter 200.

The frequency bandwidth of the power transmitted from the wireless powertransmitter 200 to the wireless power receiver 300 may be 6.78 MHz, butthe embodiment is not limited thereto.

Hereinafter, the power transmission process will be described in moredetail.

The power supply device 100 generates AC power having a predeterminedfrequency and transmits the AC power to the wireless power transmitter200.

The transmission induction coil 210 and the transmission resonant coil220 are inductively coupled with each other. In other words, if ACcurrent flows through the transmission induction coil 210 due to thepower received from the power supply apparatus 100, the AC current isinduced to the transmission resonant coil 220 physically spaced apartfrom the transmission induction coil 210 due to the electromagneticinduction.

Thereafter, the power received in the transmission resonant coil 220 istransmitted to the wireless power receiver 300, which makes a resonancecircuit with the wireless power transmitter 200, through resonance.

The transmission resonant coil 220 of the wireless power transmitter 200may transmit power to the reception resonant coil 310 of the wirelesspower receiver 300 through a magnetic field.

In detail, the transmission resonant coil 220 and the reception resonantcoil 310 are resonantly coupled with each other to be operated at theresonant frequency. Since the transmission resonant coil 220 isresonantly coupled with the reception resonant coil 310, the powertransmission efficiency between the wireless power transmitter 200 andthe wireless power receiver 300 may be significantly improved.

Power can be transmitted between two LC circuits, which areimpedance-matched with each other, that is, between the transmissionresonant coil 220 and the reception resonant coil 310 through resonance.The power transmitted through the resonance can be farther transmittedwith higher efficiency when comparing with the power transmitted by theelectromagnetic induction.

The reception resonant coil 310 receives power from the transmissionresonant coil 220 through the resonance. The AC current flows throughthe reception resonant coil 310 due to the received power. The powerreceived in the reception resonant coil 310 is transmitted to thereception induction coil 320, which is inductively coupled with thereception resonant coil 310, due to the electromagnetic induction. Thepower received in the reception induction coil 320 is rectified by therectifying circuit 330 and transmitted to the load 400.

According to one embodiment, the transmission induction coil 210, thetransmission resonant coil 220, the reception resonant coil 310, and thereception induction coil 320 may have a spiral structure in a planespiral shape or a helical structure in a three-dimensional spiral shape,but the embodiment is not limited thereto.

A quality factor and a coupling coefficient are important in thewireless power transmission. That is, the greater the quality factor andthe coupling coefficient have values, the more the power transmissionefficiency may be improved.

The quality factor may refer to an index of energy that may be stored inthe vicinity of the wireless power transmitter 200 or the wireless powerreceiver 300.

The quality factor may vary according to the operating frequency w aswell as a shape, a dimension and a material of a coil. The qualityfactor may be expressed as following equation, Q=ω*L/R. In the aboveequation, L refers to the inductance of a coil and R refers toresistance corresponding to the quantity of power loss caused in thecoil.

The quality factor may have a value of 0 to infinity. When the qualityfactor has a greater value, the power transmission efficiency betweenthe wireless power transmitter 200 and the wireless power receiver 300may be more improved.

The coupling coefficient represents the degree of inductive magneticcoupling between a transmission coil and a reception coil, and has avalue of 0 to 1.

The coupling coefficient may vary according to the relative position andthe distance between the transmission coil and the reception coil.

The wireless power transmitter 200 may exchange information with thewireless power receiver 300 through in-band or out-of-bandcommunication.

The in-band communication may refer to the communication for exchanginginformation between the wireless power transmitter 200 and the wirelesspower receiver 300 by using a signal having a frequency used in thewireless power transmission. The wireless power receiver 300 may furtherinclude a switch and may receive the power transmitted from the wirelesspower transmitter 200 through a switching operation of the switch ornot. Thus, the wireless power transmitter 200 detects an amount of powerconsumed in the wireless power transmitter 200, so that the wirelesspower transmitter 200 may recognize an on or off signal of the switchincluded therein.

In detail, the wireless power receiver 300 may change an amount of powerdissipated in a resistor by using the resistor and a switch, so that thepower consumed in the wireless power transmitter 200 may be changed. Thewireless power transmitter 200 may sense a change of the consumed powerto obtain information about a state of the wireless power receiver 300.The switch and the resistor may be connected in series to each other.The information about a state of the wireless power receiver 300 mayinclude information about a current charged amount and/or the change ofcharged amount of the wireless power receiver 300.

In more detail, when the switch is opened, the power dissipated in theresistor is 0 (zero) and the power consumed in the wireless powertransmitter 200 is also reduced.

If the switch is shorted, the power absorbed in the resistor is morethan 0 and the power consumed in the wireless power transmitter 200 isincreased. While the wireless power receiver repeats the aboveoperation, the wireless power transmitter 200 may detect the powerconsumed in the wireless power transmitter 200 and may perform digitalcommunication with the wireless power receiver 300.

The wireless power transmitter 200 receives the information about thestate of the wireless power receiver 300 according to the aboveoperation, so that the wireless power transmitter 200 may transmit thepower suitable to the reception state of the wireless power receiver300.

To the contrary, the wireless power transmitter 200 may include aresistor and a switch to transmit the information about the state of thewireless power transmitter 200 to the wireless power receiver 300.According to one embodiment, the information about the state of thewireless power transmitter 200 may include information about the maximumamount of power to be supplied from the wireless power transmitter 200,the number of wireless power receivers 300 receiving the power from thewireless power transmitter 200 and the amount of available power of thewireless power transmitter 200.

The out-of-band communication refers to the communication performedthrough a specific frequency band other than the resonance frequencyband in order to exchange information necessary for the powertransmission. The wireless power transmitter 200 and the wireless powerreceiver 300 can be equipped with out-of-band communication modules toexchange information necessary for the power transmission. Theout-of-band communication module may be installed in the power supplydevice. In one embodiment, the out-of-band communication module may usea short-distance communication technology, such as Bluetooth, Zigbee,WLAN or NFC, but the embodiment is not limited thereto.

FIG. 2 is a block diagram showing a wireless power transmission systemaccording to a second embodiment.

Referring to FIG. 2, the wireless power transmission system 20 mayinclude a power supply device 100, a wireless power transmitter 200, awireless power receiver 300 and a load 400.

The wireless power transmission system 20 shown in FIG. 2 may be asystem in which the wireless power transmitter 200 wirelessly transmitspower to the wireless power receiver 300 in an electromagnetic inductionscheme.

According to an embodiment, the power supply device 100 may be includedin the wireless power transmitter 200.

The wireless power transmitter 200 may include a transmission inductioncoil 210.

The wireless power receiver 300 may a reception induction coil 320 and arectifying circuit 330.

Both terminals of the power supply device 100 are connected to bothterminals of the transmission induction coil 210.

The transmission induction coil 210 may be spaced apart from thereception induction coil 320 by a predetermined distance.

The wireless power transmitter 200 may transmit the power provided fromthe power supply device 100 to the wireless power receiver 300 throughan electromagnetic induction scheme.

Hereinafter the power transmission process will be described in moredetail.

The power supply device 100 generates AC power having a predeterminedfrequency and transmits the AC power to the wireless power transmitter200.

The transmission induction coil 210 included in the wireless powertransmitter 200 and the transmission resonant coil 220 included in thewireless power receiver 300 are inductively coupled with each other. Inother words, if AC current flows through the transmission induction coil210 due to the power supplied from the power supply apparatus 100, amagnetic field is formed in the transmission induction coil 210 so thatthe AC current is induced to the reception induction coil 320 physicallyspaced apart from the transmission induction coil 210 due to theelectromagnetic induction to form a magnetic field. That is, the powertransmission between the transmission induction coil 210 and thereception induction coil 320 may be performed through a magnetic field.

The frequency bandwidth of the power transmitted from the wireless powertransmitter 200 to the wireless power receiver 300 may be in the rangeof 110 MHz to 205 MHz, but the embodiment is not limited thereto

The power received in the reception induction coil 320 is rectified bythe rectifying circuit 330 and transmitted to the load 400. The powertransferred to the reception induction coil 320 is AC power.

According to one embodiment, the transmission induction coil 210 and thereception induction coil 320 may have a spiral structure in a planespiral shape or a helical structure in a three-dimensional spiral shape,but the embodiment is not limited thereto

FIG. 3 is a block diagram showing a wireless power transmission systemaccording to a third embodiment.

According to the third embodiment, the wireless power transmissionsystem 30 may be a system in which the wireless power transmitter 200wirelessly transmits power in an electromagnetic induction or resonancescheme.

Referring to FIG. 3, the wireless power transmission system 30 mayinclude a power supply device 100, a wireless power transmitter 200, awireless power receiver 300 and a load 400.

According to an embodiment, the power supply device 100 may be includedin the wireless power transmitter 200.

The wireless power transmitter 200 may include a transmission inductioncoil 210 and a transmission resonant coil 220.

Both terminals of the transmission induction coil 210 may be connectedto both terminals of the power supply device 100.

The transmission resonant coil 220 may be spaced apart from thetransmission induction coil 210 by a predetermined distance.

The wireless power receiver 300 may include a reception coil 340 and arectifying circuit 330.

Both terminals of the reception coil 340 is connected to both terminalsof the rectifying circuit 330 and the load 400 is connected to bothterminals of the rectifying circuit 330. According to an embodiment, theload 400 may be included in the wireless power receiver 300.

The wireless power transmitter 200 may transmit the power provided fromthe power supply device 100 to the wireless power receiver 300 by usingan electromagnetic induction or resonance scheme.

Hereinafter the power transmission process between the wireless powertransmitter 200 and the wireless power receiver 300 will be described inmore detail.

The power supply device 100 generates AC power having a predeterminedfrequency and transmits the AC power to the transmission induction coil210 of the wireless power transmitter 200. The AC power transmitted tothe transmission induction coil 210 may be transferred to thetransmission resonant coil 220 by using an electromagnetic inductionscheme.

That is, the transmission induction coil 210 and the transmissionresonant coil 220 are inductively coupled with each other.

If AC current flows through the transmission induction coil 210 due tothe AC power received from the power supply device 100, the AC currentis induced to the transmission resonant coil 220 physically spaced apartfrom the transmission induction coil 210 due to the electromagneticinduction, so that the AC power may be transferred to the transmissionresonant coil 220.

The transmission resonant coil 220 may transmit the AC power receivedfrom the transmission induction coil 210 to the reception coil 340 ofthe wireless power receiver 300 by using a resonant or electromagneticinduction scheme.

When the transmission resonant coil 220 transmits power to the receptioncoil 340 by using a resonance scheme, the transmission resonant coil 220and the reception resonant coil 310 are resonantly coupled with eachother to be operated in the resonant frequency band. Since thetransmission resonant coil 220 is resonantly coupled with the receptionresonant coil 310, the power transmission efficiency between thewireless power transmitter 200 and the wireless power receiver 300 maybe significantly improved.

The frequency band of the power transmitted from the transmissionresonant coil 220 to the reception coil 340 by using a resonance schememay be different from that of the power transmitted from thetransmission resonant coil 220 to the reception coil 340 by using amicroelectronic induction scheme.

According to an embodiment, when the transmission resonant coil 220transmits the power to the reception coil 340 by using a resonancescheme, the frequency band of the power to be transmitted may be 6.78MHz, but the embodiment is not limited thereto.

According to an embodiment, when the transmission resonant coil 220transmits the power to the reception coil 340 by using anelectromagnetic induction scheme, the frequency band of the power to betransmitted may be in the range of 110 MHz to 205 MHz, but theembodiment is not limited thereto.

FIG. 4 is an equivalent circuit diagram of the transmission inductioncoil 210 according to an embodiment.

As shown in FIG. 4, the transmission induction coil 210 may include aninductor L1 and a capacitor C1, and a circuit having a desirableinductance and a desirable capacitance can be constructed by theinductor L1 and the capacitor C1.

The transmission induction coil 210 may be constructed as an equivalentcircuit in which both terminals of the inductor L1 are connected to bothterminals of the capacitor C1. In other words, the transmissioninduction coil 210 may be constructed as an equivalent circuit in whichthe inductor L1 is connected to the capacitor C1 in parallel.

The capacitor C1 may include a variable capacitor, and impedancematching may be performed by adjusting the capacitance of the capacitorC1. The equivalent circuit of the transmission resonant coil 220, thereception resonant coil 310 and the reception induction coil 320 shownin FIGS. 1 to 3 may be the same as the equivalent circuit shown in FIG.4.

FIG. 5 is an equivalent circuit diagram of the power supply device 100and the wireless power transmitter 200 according to an embodiment. FIG.5 is an equivalent circuit diagram of the wireless power transmitter 200shown FIGS. 1 and 3, but the wireless power transmitter 200 shown inFIG. 2 does not include the transmission resonant coil 220 shown in FIG.5.

As shown in FIG. 5, the transmission induction coil 210 and thetransmission resonant coil 220 may be constructed by using inductors L1and L2 and capacitors C1 and C2 having predetermined inductances andcapacitances, respectively.

FIG. 6 is an equivalent circuit diagram of the wireless power receiver300 according to an embodiment.

FIG. 6 is an equivalent circuit diagram of the wireless power receiver300 shown in FIG. 1, but the wireless power receiver 300 shown in FIGS.1 and 2 does not include the reception induction coil 320 shown in FIG.6.

As shown in FIG. 6, the reception resonant coil 310 and the receptioninduction coil 320 may be constructed by using inductors L3 and L4, andcapacitors C3 and C4 having predetermined inductances and capacitances,respectively.

The rectifying circuit 330 may convert AC power transferred from thereception induction coil 320 into DC power and may transfer the DC powerto the load 400.

The rectifying circuit 330 may include a rectifier and a smoothingcircuit. The rectifier may include a silicon rectifier and as shown inFIG. 4, may be equivalent to a diode D1.

The rectifier may convert AC power transferred from the receptioninduction coil 320 into DC power.

The smoothing circuit may remove AC components included in the DC powerconverted by the rectifier to output a smoothed DC power. According toan embodiment, as shown in FIG. 4, a rectifying capacitor C5 may be usedas the smoothing circuit, but the embodiment is not limited thereto.

The load 400 may be an arbitrary rechargeable battery or a devicerequiring the DC power. For example, the load 400 may refer to abattery.

The wireless power receiver 300 may be installed in an electronicdevice, such as a cellular phone, a laptop computer or a mouse,requiring the power.

FIG. 7 is a block diagram showing a power supply device according to anembodiment.

The power supply device 100 may generate AC power and supply the ACpower to the wireless power transmitter 200 illustrated in FIGS. 1 to 3.

Referring to FIG. 7, the power supply device 100 may include a powersupply unit 110, a switch 120, a DC-DC converter 130, a current sensingunit 140, an oscillator 150, an AC power generating unit 160, a storageunit 170 and a control unit 180.

The power supply unit 110 may supply DC power to each component of thepower supply device 100. The power supply unit 110 may be providedseparately from the power supply device 100.

The switch 120 may connect the power supply unit 110 with the DC-DCconverter 130, or disconnect the power supply unit 110 from the DC-DCconverter 130. The switch 120 may be opened or shorted by an open signalor a short signal of the control unit 180. According to one embodiment,the switch 120 may be open or shorted under the control of the controlunit 180 according to the power transmission state between the wirelesspower transmitter 200 and the wireless power receiver 300.

The DC-DC converter 130 may convert DC voltage, which is received fromthe power supply unit 110, into DC voltage having a predeterminedvoltage value to be output.

After converting the DC voltage received from the power supply unit 110into AC voltage, the DC-DC converter 130 may boost up or drop down andrectify the converted AC voltage, and output the DC voltage having apredetermined voltage value.

The DC-DC converter 130 may include a switching regulator or a linearregulator.

The linear regulator is a converter to receive input voltage to output arequired quantity of voltage and to discharge the remaining quantity ofvoltage as heat.

The switching regulator is a converter capable of adjusting outputvoltage through a pulse width modulation (PWM) scheme.

The current sensing unit 140 may sense the current flowing through thepower supply device 100 to measure the intensity of sensed current.

According to one embodiment, the current sensing unit 140 may measurethe intensity of current flowing when the DC voltage output from theDC-DC converter 130 is applied to the AC power generating unit 160, butthe embodiment is not limited thereto. In other words, the currentsensing unit 140 may measure the intensity of current output from the ACpower generating unit 160.

According to an embodiment, the current sensing unit 140 may include acurrent transformer (CT). According to an embodiment, the intensity ofcurrent applied to the AC power generating unit 160 may be utilized tofind out the distance between the wireless power transmitter 200 and thewireless power receiver 300. According to an embodiment, the intensityof current applied to the AC power generating unit 160 may be utilizedto find out a coupling coefficient between the wireless powertransmitter 200 and the wireless power receiver 300. According to anembodiment, the intensity of the current applied to the AC powergenerating unit 160 may serve as an index to represent the couplingstate between the wireless power transmitter 200 and the wireless powerreceiver 300. The coupling state may be used to obtain the couplingcoefficient between the wireless power transmitter 200 and the wirelesspower receiver 300.

The current sensing unit 140 may transfer the signal corresponding tothe intensity of the sensed current to the control unit 180.

Although the current sensing unit 140 is depicted in FIG. 7 as anelement separated from the control unit 180, the current sensing unit140 may be embedded in the control unit 180.

The oscillator 150 may generate an AC signal having a predeterminedfrequency and apply the AC signal to the AC power generating unit 160.

The AC power generating unit 160 may convert the DC voltage transferredfrom the DC-DC converter 130 into the AC voltage.

The AC power generating unit 160 may amplify the AC signal generatedfrom the oscillator 150. A degree of amplifying the AC signal may bevaried according to the DC voltage applied through the DC-DC converter130.

According to an embodiment, the AC power generating unit 160 may includea push-pull type dual MOSFET.

The control unit 180 may control the overall operation of the powersupply device 100.

The control unit 180 may control the DC-DC converter 130 so that presetDC voltage is applied to the AC power generating unit 160.

When the DC voltage output from the DC-DC converter 130 is applied tothe AC power generating unit 160, the control unit 180 may receive asignal, which corresponds to the intensity of flowing current, from thecurrent sensing unit 140, and may adjust the DC voltage output from theDC-DC converter 130 and the frequency of the AC signal output from theoscillator 150 by using the received signal.

The control unit 180 receives the signal, which corresponds to theintensity of the current applied to the AC power generating unit 160,from the current sensing unit 140 to determine if the wireless powerreceiver 300 exists. That is, the control unit 180 may identify whetherthe wireless power receiver 300 capable of receive power from thewireless power transmitter 200 based on the intensity of the currentapplied to the AC power generating unit 160 exists.

The control unit 180 may control the oscillator 150 such that an ACsignal having a predetermined frequency is generated. The predeterminedfrequency may refer to a resonance frequency of the wireless powertransmitter 200 and the wireless power receiver 300 when the powertransmission is performed by using resonance.

The storage unit 170 may store the intensity of the current applied tothe AC power generating unit 160, the coupling coefficient between thewireless power transmitter 200 and the wireless power receiver 300, andthe DC voltage output from the DC-DC converter 130 corresponding to eachother. That is, the storage unit 170 may store the current intensity,the coupling coefficient and the DC voltage in the form of a look-uptable.

The control unit 180 may search for a coupling coefficient correspondingto the intensity of the current applied to the AC power generating unit160 and DC voltage output from the DC-DC converter 130 in the storageunit 170, and may control the DC-DC converter 130 so that the searchedDC voltage may be output.

Hereinafter an embodiment of the wireless power transmitter 200 will bedescribed with reference to FIGS. 1 to 7.

FIG. 8 is an exploded perspective view showing a wireless powertransmitter according to an embodiment. FIG. 9 is a plane projectionview showing a wireless power transmitter according to an embodiment.

Referring to FIGS. 8 and 9, a wireless power transmitter 200 may includea power supply device 100, a transmission coil 230, a magnet 240, atransmission coil receiving unit 250, a shielding unit 260, an inletdevice 270, a case 280 and a heat radiation member 290.

The power supply device 100 may generate AC power and supply the ACpower to the transmission coil 230. In an embodiment, the power supplydevice 100 may include the elements illustrated in FIG. 7. The elementsof the power supply device 100 may be disposed on a printed circuitboard (PCB) and may be electrically connected to a wire layer of thePCB.

In detail, the power supply device 100 may include a power inductorwhich serves as the DC-DC converter 130, a matching capacitor formatching a frequency of power transmitted to the transmission coil 230,and a transmission circuit including the elements illustrated in FIG. 7.The power inductor, the matching capacitor and the transmission circuitmay be mounted on the PCB.

The transmission coil 230 may wirelessly transmit the power receivedfrom the power supply device 100 to a wireless power receiver (notshown).

When the wireless power transmitter 200 transmits power to the wirelesspower receiver (not shown) through an electromagnetic induction scheme,the transmission coil 230 may correspond to the transmission inductioncoil 210 of FIG. 2. When the wireless power transmitter 200 transmitspower to the wireless power receiver (not shown) through a resonancescheme, the transmission coil 230 may correspond to the transmissionresonant coil 220 of FIG. 1. A transmission induction coil 210 may befurther disposed to one side adjacent to the transmission coil 230.

In an embodiment, the transmission coil 230 may have one of the spiraland helical structures, but the embodiment is not limited thereto.

The magnet 240 may be disposed inside the transmission coil 230 so thatthe transmission coil 230 and the reception coil included in thewireless power receiver 300 may be arranged. In this case, a magnet maybe provided even to the wireless power receiver. Due to the magneticforce between the magnets of the transmission coil 230 of the wirelesspower transmitter 200 and the wireless power receiver 300, the distancebetween the transmission coil 230 and the reception coil may beminimized.

For example, when a user places a terminal including the wireless powerreceiver on the wireless power transmitter 200 to charge the terminal,due to the magnetic force between the magnets of the wireless powertransmitter 200 and the wireless power receiver 300, the reception coilof the wireless power receiver 300 may be adjacent to the transmissioncoil 230 of the wireless power transmitter 200, so that the terminal maybe charged at a high power transmission efficiency.

The receiving unit 250 may be disposed at a lower case, which will bedescribed below, to receive the transmission coil 230 and the magnet240. That is, the receiving unit 250 may include a transmission coilreceiving unit 251 for receiving the transmission coil 230 and a magnetreceiving unit 253 for receiving the magnet 240.

As shown in FIG. 8, the transmission coil receiving unit 251 and themagnet receiving unit 253 may have cylindrical shapes with upperportions open, but the embodiment is not limited thereto. In addition,the transmission coil receiving unit 251 and the magnet receiving unit253 may have various shapes according to the shapes of the transmissioncoil 230 and the magnet 240.

The shield unit 260 may be disposed below the receiving unit 250 tochange a direction of a magnetic field formed on the transmission coil230 into a side direction, so that the magnetic field may beconcentrically transferred to the wireless power receiver.

Further, the shielding unit 260 may absorb a part of the magnetic fieldformed on the transmission coil 230 and radiate the absorbed magneticfield as heat, so that an amount of the magnetic field exposed to anoutside may be reduced. Due to the shielding unit 260, a part of themagnetic field formed on the transmission coil 230 is inhibited fromleaking to an outside, so that the leakage of the magnetic field harmfulto human health may be minimized.

According to an embodiment, the shielding unit 260 may include aferrite-type magnetic substance or a sandust-type magnetic substance,but the embodiment is not limited thereto.

The inlet device 270 may be disposed on one side of the transmissioncoil 230 to provide air to the transmission coil 230, so that the heatgenerated from the transmission coil 270 may be radiated.

The inlet device 270 may periodically provide air to the transmissioncoil 230 so that the heat generated from the transmission coil 270 maybe radiated to an outside. That is, since the transmission coil 230includes a resistance component, as current flows through thetransmission coil 230, heat is generated due to the resistancecomponent. In this case, the inlet device 270 may radiate the heatgenerated by the resistance component of the transmission coil 230 to anoutside.

According to an embodiment, the inlet device 270 may be a blower forblowing out air forcedly generated through a pumping to the transmissioncoil 230.

According to an embodiment, the inlet device 270 may be a fan forproviding air to the transmission coil 230 through an impeller.

A process of radiating the heat generated from the transmission coil 230to an outside through the inlet device 270 will be described below.

The case may include a lower case 281 and an upper case 283.

The power supply device 100, the transmission coil 230, the magnet 240,a receiving unit 250, the inlet device 270 and the heat radiation member290 are disposed in the lower case 281.

The upper case 283 may be coupled to the lower case 281. In detail, theupper case 283 may include first and second passage grooves 283 a and283 b. The upper and lower cases 283 and 281 may be coupled to eachother by coupling the transmission coil receiving unit 251 of the lowercase 281 to the first passage groove 283 a of the upper case 283.

The inlet device 270 and the first and second passage grooves 283 a and283 b are called a radiation unit, but the embodiment is not limitedthereto.

An area formed by the first passage groove 283 a may correspond to anarea formed by the transmission coil receiving unit 251.

The first passage groove 283 a may be in a form of surrounding an outerperiphery of the transmission coil 230.

An inlet portion A through which air is input from the inlet device 270may be formed at one side of the firs passage groove 283 a, and anoutlet portion B through which the air input through the inlet portion Ais output into the second passage groove 283 b may be formed at anopposite side of the first passage groove 283 a.

The second passage groove 283 b may communicate with the outlet portionB so that the air blowing out through the outlet portion B may be outputto an outside of the wireless power transmitter 200.

The second passage groove 283 b may have a straight line shape.

The second passage groove 283 b may radiate heat dispersed from the heatradiation member 290 described below. The heat radiation member 290 mayhave a sheet shape.

The heat radiation member 290 may be disposed over the power supplydevice 100 so that the heat radiation member 290 may radiate the heatgenerated from the power supply device 100 to the outside. In detail,the heat radiation member 290 may have an area corresponding to that ofthe power supply device 100 and may disperse the heat generated from thepower supply device 100 in x-y plane direction to guide the dispersedheat toward the second passage groove 283 b of the upper case 283. Theheat dispersed by the heat radiation member 290 is guided into thesecond passage groove 283 b of the upper case 283, so that the heat maybe radiated to an outside.

A groove 291 having a shape corresponding to that of the second passagegroove 283 b of the upper case 283 may be formed in the heat radiationmember 290. That is, the heat generated by the power supply device 100and dispersed by the heat radiation member 290 may be introduced intothe groove 291, so that the heat introduced into the groove 291 may beradiated to an outside through the second passage groove 283 b.

According to an embodiment, the heat radiation member 290 may be formedof a material including one of graphite, boron nitride and silicon.

According to an embodiment, the wireless power transmitter 200 may befabricated in a pad shape. When a terminal having the wireless powerreceiver is positioned on the wireless power transmitter 200 formed inthe pad shape, the battery installed in the terminal may be easilycharged.

Next, a process of radiating heat generated in the wireless powertransmitter 200 will be described in detail with reference to FIGS. 8and 9.

FIG. 10 is a plane projection view of the wireless power transmitter 200for the purpose of illustrating a process of radiating heat generatedfrom the wireless power transmitter 200 according to an embodiment.

Referring to FIG. 10, air is introduced into the inlet portion A of thefirst passage groove 283 a through the inlet device 270. The inletdevice 270 may periodically allow air to flow into the inlet portion Aof the first passage groove 283 a.

The air input to the inlet portion A flows into the outlet portion B ofthe first passage groove 283 a along the first passage groove 283 a andthe heat radiated from the outlet portion B flows out to an outsidethrough the second passage groove 283 b. In this case, the heatgenerated from the transmission coil 230 may flow into the first passagegroove 283 a and the inflow heat may be radiated to an outside throughthe second passage groove 283 b communicating with the outlet portion Bof the first passage groove 283 a.

Further, the heat generated from the power supply device 100 anddispersed by the heat radiation member 290 may flow into the groove 291of the heat radiation member 290 and introduced into the groove 291 ofthe heat radiation member 290, so that the heat flowing into the groove291 may flow into the second passage groove 283 b to be radiated to anoutside.

As described above, the wireless power transmitter 200 may radiate theheat generated from the transmission coil 230 and the power supplydevice 100 so that the internal temperature of the wireless powertransmitter 200 may be decreased, so the wireless power transmitter 200may be inhibited from being deteriorated.

In addition, when the terminal including the wireless power receiver onthe wireless power transmitter 200 having the pad shape is charged, theheat generated from the wireless power transmitter 200 may be inhibitedfrom transferring to the terminal.

Hereinafter the temperature reduction in the wireless power transmitter200 according to the embodiment will be described with reference toFIGS. 11 to 13.

FIG. 11 is a view illustrating a variation of temperature near thetransmission coil 230 according to whether the wireless powertransmitter of the embodiment is used.

FIG. 11 (a) shows an experiment result of temperature near thetransmission coil 230 when the wireless power transmitter 200 of theembodiment is not used. FIG. 11 (b) shows an experiment result oftemperature near the transmission coil 230 when the wireless powertransmitter 200 of the embodiment is used.

The experiment results of FIG. 11 are obtained when the transmissioncoil 230 transmits power to a receiving part through an electromagneticinduction scheme.

The calorific value of the transmission coil 230 is 230,000 Watt/m³under a basic experiment condition, the calorific value of the powerinductor (FET) is 200,000 Watt/m3, the calorific value of the matchingcapacitor is 50,000 Watt/m³, a natural convection coefficient of thecase 280 is 5 Watt/(m2K), and external temperature is 25°.

Material properties of the elements of the wireless power transmitter200 will be described with reference to FIG. 12.

FIG. 12 is a view showing properties of the elements of the wirelesspower transmitter 200 according to an embodiment.

FIG. 12 shows materials and thermal conductivities of each element ofthe wireless power transmitter 200.

When comparing FIG. 11 (a) with FIG. 11 (b), the temperature near thetransmission coil 230 is 62.1° C. when the wireless power transmitter200 is not used, but the temperature near transmission coil 230 is 47.1°C. when the wireless power transmitter 200 is used, so that thetemperature of about 15° C. is decreased. That is, the heat generatedfrom the transmission coil 230 due to the configuration of the wirelesspower transmitter 200 is radiated to an outside so that the temperaturenear the transmission coil 230 may be decreased.

FIG. 13 is a view illustrating a variation of temperature near the powersupply device 100 according to whether the wireless power transmitter200 of the embodiment is used.

FIG. 13 (a) shows an experiment result of temperature near the powersupply device 100 when the wireless power transmitter 200 of theembodiment is not used. FIG. 13 (b) shows an experiment result oftemperature near the power supply device 100 when the wireless powertransmitter 200 of the embodiment is used.

Since the experiment condition of FIG. 13 is the same as that of FIGS.11 and 12, the detailed description will be omitted.

When comparing FIG. 13 (a) with FIG. 13 (b), the temperature near thepower supply device 100 is 40° C. when the wireless power transmitter200 is not used, but the temperature near the power supply device 100 is29° C. when the wireless power transmitter 200 is used, so that thetemperature of about 11° C. is decreased. That is, the heat generatedfrom the power supply device 100 due to the configuration of thewireless power transmitter 200 is radiated to an outside so that thetemperature near the transmission coil 230 may be decreased.

According to the embodiment, the heat is radiated from the transmissioncoil so that the wireless power transmitter and the wireless powerreceiver may be inhibited from being deteriorated.

The transmission coil and the reception coil provided in the wirelesspower receiver may be effectively arranged through the magnet disposedinside the transmission coil, so that the power transmission efficiencymay be improved.

Meanwhile, any other various effects will be directly and implicitlydescribed below in the description of the embodiment.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A wireless power transmitter comprising: a firstcase; a coil on the first case; a first passage groove having a shapecorresponding to a shape of the coil; and a second case coupled to thefirst case.
 2. The wireless power transmitter of claim 1, furthercomprising a coil receiving unit on the first case to receive the coil,wherein the first passage groove is coupled to the coil receiving unit.3. The wireless power transmitter of claim 2, wherein the coil issurrounded by the first passage groove and the coil receiving unit. 4.The wireless power transmitter of claim 2, further comprising: a magnetinside the coil; and a magnet receiving unit on the first case toreceive the magnet.
 5. The wireless power transmitter of claim 4,further comprising a shielding unit below the coil receiving unit andthe magnet receiving unit.
 6. The wireless power transmitter of claim 1,wherein the first passage groove surrounds an outer periphery of thecoil.
 7. The wireless power transmitter of claim 1, wherein the firstpassage groove is provided on the second case.
 8. The wireless powertransmitter of claim 1, wherein the first passage groove has aclose-loop structure.
 9. The wireless power transmitter of claim 1,further comprising an inlet device connected to one side of the firstpassage groove to inject air into the first passage groove.
 10. Thewireless power transmitter of claim 9, further comprising: a powersupply device connected to the coil to supply power to the coil; a heatradiation member on the power supply device; and a second passage grooveconnected to an opposite side of the first passage groove and disposedon the heat radiation member.
 11. The wireless power transmitter ofclaim 10, wherein the heat radiation member includes a groove having ashape corresponding to a shape of the second passage groove.
 12. Thewireless power transmitter of claim 11, wherein the second passagegroove is disposed in the groove of the heat radiation member.
 13. Thewireless power transmitter of claim 10, wherein the heat radiationmember has an area corresponding to an area of the power supply device.14. The wireless power transmitter of claim 10, wherein the firstpassage groove includes first and second sub-passage grooves, the firstand second sub-passage grooves divided from each other at a first inletunit connected to the inlet device and met with each other at a secondinlet unit connected to the second passage groove.
 15. The wirelesspower transmitter of claim 9, wherein the inlet device includes one of ablower and a fan.
 16. A wireless power transmitter, comprising: atransmission coil to wirelessly transmit power to a wireless powerreceiver; an inlet device on one side of the transmission coil to supplyair to the transmission coil; and a radiation unit to radiate heat ofthe transmission coil by changing a movement path of the supplied air.17. The wireless power transmitter of claim 16, wherein the radiationunit includes a first passage groove connected to the inlet device. 18.The wireless power transmitter of claim 17, wherein the first passagegroove has a close loop structure corresponding to a shape of thetransmission coil.
 19. The wireless power transmitter of claim 17,further comprising: a power supply device to supply power to thetransmission coil; and a second passage groove connected to the firstpassage groove and disposed on the power supply device.
 20. The wirelesspower transmitter of claim 19, wherein the first and second passagegrooves are disposed on a case.